1. Field of the Invention
The present invention relates to an improved method for the production of vanadium/phosphorus mixed oxide catalysts where a catalyst precursor is formed by a sequential procedure in which a solid phase vanadium +5 compound such as V.sub.2 O.sub.5 is suspended in an organic solvent and digested under reflux in the presence of phosphoric acid under anhydrous conditions for a certain period, and thereafter water is added to the suspension of solid in solvent and the resulting mixture is further digested under reflux to complete the catalyst precursor formation; the catalyst after activation has special utility in the production of maleic anhydride.